<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>Document</title>
</head>
<body>
	<form action="">
		<p>
			只允许输入数字
			<input type="text" onkeyup="this.value = this.value.replace(/\D/g,'')">
		</p>
		<p>
			只允许输入英文
			<input type="text" onkeyup="this.value = this.value.replace(/[^a-zA-Z]/g,'')">
		</p>
		<p>
			只允许输入汉字
			<input type="text" onkeyup="this.value = this.value.replace(/[^\u4e00-\u9fa5]/g,'')">
		</p>
	</form>
</body>
</html>